package chapter23.h23_1.language;

import java.util.StringTokenizer;

public class Context implements ExecutorFactory{
    private ExecutorFactory factory;
    private StringTokenizer tokenizer;
    private String currentToken;

    public Context(String text){
        tokenizer = new StringTokenizer(text);
        nextToken();
    }

    public String nextToken() {
        if (tokenizer.hasMoreTokens()) {
            currentToken = tokenizer.nextToken();
        }else {
            currentToken = null;
        }
        return  currentToken;
    }

    public String currentToken(){
        return currentToken;
    }

    public void skipToken(String token) throws ParseException {
        if (!token.equals(currentToken)){
            throw new ParseException("Warning: "+token+" is expected, but "+currentToken+" is found.");
        }
        nextToken();
    }

    public int currentNumber() throws ParseException{
        int number = 0;
        try {
            number = Integer.parseInt(currentToken);
        }catch (NumberFormatException e){
            throw new ParseException("Warning: " + e);
        }
        return number;
    }

    public void setExecutorFactory(ExecutorFactory factory){
        this.factory = factory;
    }

    @Override
    public Executor createExecutor(String name) {
        return factory.createExecutor(name);
    }
}
